Landsat Looks and Sees

Forty Years of Observations Reveal a Changing Planet and Society

You can see a lot by just looking. —Yogi Berra

By Joel N. ShurkinDesign by Robert SimmonJuly 23, 2012

In 2011, scientists from North Carolina, France, and Peru saw that deforestation in a portion of the Amazon rainforest was proceeding at an unusual pace in an unexpected place. Images from the Landsat 5 satellite clearly showed that deforestation had increased six-fold over a six-year period in the remote Madre de Dios region of Peru, near the Bolivian border. No one knew why.

Compelled by the images, investigators visited the forest and found serious mercury poisoning affecting both the people and the wildlife. Driven by soaring gold prices, miners were clearing trees for gold. The result was not only further deforestation, but mercury pollution from the mining process.

Landsat actually did not see the mercury pollution; it saw deforestation where it should not have been happening. And Landsat compelled the scientists to investigate.

Without Landsat, America’s longest running Earth-imaging satellite program, it is unlikely scientists would have seen the pollution or the deforestation at Madre de Dios for years, and the health of local residents would have been seriously affected. Landsat may have saved lives.

Since 1972, Landsat has collected more than three million images that describe two generations of human imprints on Earth, as well as the planet’s effects on humanity. The Landsat archives tell an unparalleled story of the planet’s land surfaces, and they are a practical, thought-provoking reservoir of things we need to watch for and to be warned of. The imagery tells a story rich in information that can help us better find ways to peacefully and prosperously accommodate seven billion people on one small planet.

A Photo Began It

It is said that the Landsat program was inspired by photographs taken by the Apollo astronauts. Those pictures showed a glorious, glowing blue orb hanging in the infinite black of space. It was a series of photos that changed forever how we view our world.

This photograph of the southwestern United States, taken in November 1966 during the Gemini XII mission, was among those that inspired the Landsat program. (NASA Astronaut photograph from the March to the Moon collection.)

Stewart Udall, United States Secretary of the Interior for Presidents Kennedy and Johnson, remembered one particular image: a picture of pollution spewing from power plants in the Four Corners area of his home state of Arizona. Knowing there was pollution on Earth was one thing; seeing it unambiguously from orbit was an entirely different matter. Clearly, satellites provided a new way to look at our home as we never had before.

The idea was not entirely new. In 1951, the British science fiction author Arthur C. Clarke suggested that satellites orbiting over the poles could take measurements and pictures of the world as it rotated below. In the mid-1960s, Udall urged the Johnson Administration to do just that: create a program of Earth-observation satellites. A joint program between the Department of Interior and NASA eventually produced the Earth Resources Technology Satellite (ERTS), which would take broad images of the Earth’s surface.

By July 23, 1972—twenty-one years after Clarke envisioned it—an Earth-watching, civilian science satellite was launched into a near-polar orbit. ERTS instruments recorded information in four spectral bands: red, green, and two infrared. More than 300 researchers—a third of them from outside the United States—were employed to analyze the new data, partly because no scientist had seen the likes before. The satellite operated until 1978, its longevity and the quality of the pictures exceeding all expectations.

During a January 1975 press briefing, NASA Associate Administrator Charles Mathews told reporters that upon launch ERTS-B would become Landsat 2, and the orbiting ERTS would be designated Landsat 1. Matthews explained that a planned mission to study the oceans was going to be called Seasat, so NASA decided it was appropriate to rename its land sensing program Landsat.

An early discovery by Landsat 1 was a tiny, previously unknown island off the coast of Newfoundland. When a Canadian scientist was lowered some years later from a helicopter to explore the island, he discovered that the only inhabitant, a polar bear, was unhappy with the intrusion. The bear charged, and the scientist left quickly. The island was named Landsat Island.